HR: 0800h
AN: A31C-0075    [Abstracts]
TI: Direct Observations of Heterogeneous Dust Processing in the Troposphere: Ambient Measurements, Source Compositions and Laboratory Studies
AU: * Sullivan, R C
EM: rcsulliv@ucsd.edu
AF: University of California, San Diego, Department of Chemistry and Biochemistry, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Guazzotti, S
EM: serad@ucsd.edu
AF: University of California, San Diego, Department of Chemistry and Biochemistry, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Sodeman, D
EM: dsodeman@ucsd.edu
AF: University of California, San Diego, Department of Chemistry and Biochemistry, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Coffee, K
EM: coffee3@llnl.gov
AF: Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, CA 94550 United States
AU: Holecek, J
EM: jholecek@ucsd.edu
AF: University of California, San Diego, Department of Chemistry and Biochemistry, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Spencer, M
EM: mtspence@ucsd.edu
AF: University of California, San Diego, Department of Chemistry and Biochemistry, 9500 Gilman Drive, La Jolla, CA 92093 United States
AU: Prather, K A
EM: kprather@ucsd.edu
AF: University of California, San Diego, Department of Chemistry and Biochemistry, 9500 Gilman Drive, La Jolla, CA 92093 United States
AB: The size and chemical composition of single dust particles in both background marine air and during dust events was determined using Aerosol Time-of-Flight Mass Spectrometry (ATOFMS) throughout the Indian and Pacific Oceans and Pacific coast during three major field campaigns: INDOEX, ACE-Asia and CIFEX. In general the chemical associations within individual particle spectra for the major dust particle types were very similar in all sampling locations. The dust mass spectra were dominated by various combinations of potassium, calcium, iron, and aluminum, with contributions from silicates, sodium, chloride and titanium oxides. The relative ion intensities often differed suggesting that the dust is a complex, externally mixed aggregate of varying mineral origins. Evidence of heterogeneous processing of the dust particles was also observed with ATOFMS using markers for nitrate, sulphate, and organic species. Aging of dust particles can dramatically alter their radiative and cloud-forming properties, changing the effects that dust will have on global climate. The dust spectra were also compared with those measured from collected dust, sand and soil samples in Asia and the United States. In general the mass spectra of the ambient and source dust particles were very similar, except that for the most part the source samples lacked evidence of atmospheric aging. Preliminary lab studies examining heterogeneous processing of dust in a flow tube will be presented. These studies investigate the relative reactivity of the different types of dust observed in the atmosphere and the competitive heterogeneous chemistry of dust and sea salt particles.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0305 Aerosols and particles (0345, 4801)
DE: 0317 Chemical kinetic and photochemical properties
DE: 0365 Troposphere--composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting